Corrosion inhibitor



nited States CORRUSEON ENHIBITOR DArcy A. Shock and John D. Sud'nury, Ponca City, Okla, assignors to Continental Oil Company, Ponca City, Okla, a corporation of Delaware Application November 23, 1953, Serial No. 393,007

18 Qiairns. (Cl. 10614) The present invention relates to compositions for and .a method of inhibiting corrosion therewith, more particularly for inhibiting corrosion in the cargo compartments of steel tankers in marine service for transporting hydrocarbon liquids.

At the present time there is a tremendous problem present in the shipping industry which is concerned with marine tankers transporting liquid hydrocarbon cargoes.

Great expense is incurred anually for upkeep and repair of the internal structures of such vessels in contact with these cargoes. Such structures are continuously undergoing severe corrosion so that much time and revenue are lost by necessity for frequently taking the tankers out of service for overhaul and repair of damages result ing from corrosion.

in the case of petroleum cargo tankers, this problem is especially acute since the hydrocarbon liquids transported are often corrosive toferrous metals, a situation which is aggravated by the presence of vagrant sea water in the ship as well as such cargoes usually containing a water impurity from other source prior to loading.

Tankers transporting the lighter petroleum distillates,

,gramming, only about 20 years of service can be expected.

Furthermore, ship maintenance costs during the 10 years ciean service may amount to as much as $1,000,000. 7

When the type of cargo is changed, e.;g., as in going to kerosene following gasoline transport or to distillates after crudes, it is common practice to clean the cargo compartments shortly after discharge of a particularcargo. The most common methodof cleaning now in use on'oil tankers is known as Butterworthing after its inventor. This system consists in a fixed installation of piping to the tanker compartments and to which a revolving nozzle an .rangement is attached. By this means the Walls of a cargo compartment are sprayedwithseawaterheated to about 180" F. and under a pressure of about 100 p. s. i..g. for about 1 /2 hours each, with therundown washpumped overboard. This is usually done when the tanker is sailing empty after a port of delivery. The combined rinsing :and scouring effect of the high velocity stream .of hot sea water serves to remove residual cargo and knocks off :rust and scale. Thus exposed,,the fresh metal surfaces are subject to immediate corrosive attack.

In the case of. tankers returning empty,.it is also necessary to fill a number of the compartments with ballast, using sea water, to stabilize and' trim the ship. These ballast tanks are then'subject to the worst of corrosive conditions.

Thus it will be seen thatoil tankers are subject to a variety of internal corrosion conditions, the influence, of

"ice

which causes rapid deterioration of the bulkheads and structural members, resulting in serious economic loss due to the expense of repair and time lost when out of service for such repair.

Methods heretofore employed in an attempt to inhibit this corrosion include:

1. Treatment of all of the cargo with a corrosion inhibitotz-This is excellent protection while acargo is abroad but leaves scant if any protection after cargo'is discharged when protection is most needed. For that reason, treatment of cargo with inhibitor is undesirable, and furthermore, it is too expensive for degreeofprotection achieved.

2. Tank c0atings.Th is method is etfective but its; cost is prohibitive except on specialty parts.

3. Inorganic inhibitor .sprays.Aqueous sodium vdichromate or alkaline sodium nitrite sprays have been used on a number of ships with limited success; such treatment involving a chemical reaction of this type has only short-lived transient effectiveness.

Accordingly, it is an object of this invention to provide a method of increasing the life and efficiency of steel cargo carrying marine vessels by inhibiting and materially reducing the commonly prevalent internal corrosion of such cargo tankers.

-It is another object of our invention to provide an improved composition for inhibiting corrosion of metal cargo compartments of oil tankers.

Another object of the present invention is to .provide an inexpensive and industrially feasible method of inhibiting corrosion of internal bulkheads and structural members of steel cargo tankers.

A further object of this invention is to provideanimproved composition for effectively inhibiting corrosion of metal surfaces, which metal surfaces are subject to-corrosive influences such as present under atmospheric and marine conditions generally.

Other objectswillappear as the description proceeds.

To the accomplishment of the foregoing and related ends, this invention then comprises the features hereinafter fully described and particularly pointed out in the. claims,

the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the invention maybe employed.

In thedrawings, Figure l is a graphic interpretationof laboratory inhibitor evaluation; Figure 2 is a graphic representation of corrosion control aboard an oil tanker. These figures are referred to in detail hereinafter.

Broadly stated, this invention comprises the preparation of an improved corrosion inhibiting composition which, in an undiluted or concentrated form, contains (l);a hydrocarbon oil, (2) an alkali or alkaline earth metal sulfonate of benzene alkylated-with a polymer of propylene, and (3) an organic additiveacting as a tackifier to increase the adhesiveness to metal of the compositionand thereby form a tenacious corrosion inhibiting film. 1T5his corrosion inhibitor composition, before a protective-flip" iplication to metal surfaces, is preferably dissolved in a volatile organic solvent such as naphtha, gasoline, and

the like. It may also, but with less effective utilization, be emulsified with Water, which in some instances -may need the addition of an emulsifying or dispersing agent to insure formation and stability of such an emulsion.

The alkylated benzene sulfonate referred to ;above,,,and

which provides the essential inhibitor component,of this 3 The alkylation of benzene (usually used in considerable excess) with such polymerized fractions is well known in commercial practice, .for example, by the use of an anhydrous aluminum chloride alkylation catalyst, or by the use of any other catalyst known to effect the olefinbenzene condensation reaction, the processing conditions of any of which may be found in the literature.

However, for the production of the present corrosion inhibiting compositions, we are concerned here with the nature of thecrude alkylates which are formed. When benzene is alkylated, for example with a close boiling dodecene fraction, the crude product obtained is composed of in the order of boiling range, (a) unreacted benzene, (b) lower disproportionation products comprising non-aromatics (naphthenes and open chain saturates) and C to C alkyl benzene, (c) dodecylbenzene,

and (d) a substantially dist-illable bottoms (A. S. T. M. boiling range about 600-770 F.) which, is commonly referred to as fpolydodecylbenzene. Although this term is somewhat inaccurate, it will be so used in the specification and the appended claims. Actually this polydodecylbenzene consists predominantly of high molecular weight branched chain alkyl benzenes, the principal components being di-C -benzene (both p and m isomers) or higher and mono-C -benzene; the increase from charged dodecene. C to C resulted from the disprolportionation reactions taking place during the alkylation process. The quantity of polydodecylbenzene bottoms produced, and the relative proportions of its indicated components, have been noted to vary somewhat with the ratio of benzene to dodecene employed in the alkylation; likewise the molecular weight may vary between about 325 and 450. These constitutional variations were observed generally for ratios of benzenezC polymer olefin from about 4:1 to aboutz'g1. The nature of the polydodecylbenzene bottoms is not expected to vary substantially from the above when employing C -polyme1s within the range of about C to C olefins in the alkylation with benzene.

We have discovered that the alkali and alkaline earth metal salts of the sulfonates of the foregoing described polydodecylbenzene are unusually good inhibitors of corrosion when compounded as indicated in accordance withfour invention, especially so under the extreme conditions induced by marine and the like salty environments. To form the sulfonate, the polydodecylbenzene is subjected to the usual s'ulfonation processes which employ concentrated or fuming sulfuric acid, or S0 and the like, and needs no further description here. The resultingpolydodecylbenzene sulfonic acid is converted to the sodium (or calcium) salt with caustic soda (or lime) in a usual way; salts of other metals (including ammonia) of groups I and II of the periodic table may be similarly prepared. The molecular weights of these sul- 'fonate salts will range from about 400 to about 700;

We! have also'observed some desirable differences in favor of the polydodecylbenzene sulfonates produced at lowfmole ratio benzene:C polymer olefin alkylationf The inhibitor compositions produced from the lower mole ratio sulfonates. appear to have. an even greater lasting effect in the protection of ferrous metal surfaces; they are more. readily emulsifiable inwater for the preparation of the aqueous type of spray material while solubility in volatile organic solvents is unaffected.

The oil portion of the inhibiting composition is made up of any ofthe so-calledmineral or hydrocarbons oils of lubricating oil viscosity. Mineral oil is meant to inelude oils refined from. any of the various crude oils by the usual refining processes including'distillation, solventextraction, acid treatment, clay treatment, dewaxing and'the like. Pale oil in the viscosity range of about 90-200 Saybolt seconds'universalat 100 F. is predecarboxylation of resin acids.

an oil-so1uble polar organic compound containing at least one long chain alkyl group having from 8 to about 24 carbon atoms. A preferred class of materials consists of the substituted ammonium salts of high molecular Weight aliphatic acids, particularly the aliphatic salts of a viscous high molecular weight primary amine derived from rosin. Rosin amiens are prepared by reacting dehydrogenated rosin acids with ammonia to formammonium salts which upon dehydration form the nitrile and then hydrogenating the rosin nitrile to produce a primary amine. A particularly effective tackifier, which we prefer to use, is the salt of this amine with stearic acid; the corresponding salts of other acids such as oleic, lauric, and naphthenic acids are also effective. These rosin amine salts are available from Hercules Powder Company or may be produced from their product designated Rosin Amine D. Somewhat more specifically Rosin Amine D is a primary amine obtained from a special grade of modified rosin. It is insoluble in water but soluble in many organic solvents and generally contains about-88-95% of resin amine, the impurities being the normal non-acid constituents of refined wood rosin and small amounts of saturated oils resulting from Typical analysis and physical properties of this product are as follows:

Physical state Viscous yellow liquid. Color Pale yellow. Density at 25 C 0.997 Refractive index at 20 C 1.5410. Nitrogen content 42-45%. Bromine number (DBr-KBrO 49. Viscosity at 25 C 4670 centistokes. Boiling range (5 mm.) 187-211 C. Boiling range (mm) 270-291 C. Boiling range (760 mm.) 344 C. (partial decomposition) Flash point (Cleveland open cup) 192 C. Heat of vaporization 20,100 calories per a mole. Neutralization equivalent 317.

Other classes of materials and examples thereof whichare useful as the tackifier component of'our inhibitor compositions are listed as follows: (1) High molecular isobutylene polymers such as Paratac produced by Enjay Company, Inc., of New York. Physical'properties of Paratac are as follows:

Viscosity at 210 F., Saybolt sec 1,300 Flash point F 400 Pour point F 10 Specific gravity at 60 0.892

(2) The gelling compositions of aluminum-naphthenate and -palmitate such as Napalm disclosed in the'Feiser Patent 2,606,107 issued August 5, 1952, (3) magnesium and aluminum soaps, e. g., the ricinoleates, (4) rosin derived alcohols such as Abitol. Abitol is a hydroabiethyl alcohol. Its physical properties are as follows:

Hydroxyl value, percent 4.95. Hydroabietyl alcohol content, percenL- 85-90. Saponification number :(diethylene glycol method) 5-14. Acid number 0.1-0.4. Methoxyl value 0.5-1.2. Unsaturation, weight percent absorbed:

Hydrogen 0.60-0.75. Bromine 12-3-0. Color (SO-mm. tube)-Lovibond 0.5 Amber.

U. S. rosin standard Z Softening point*(Hercules drop method) 33 C. '(9 1 F.). Specific gravity at 20/ 20 C 1.007-1.008. Refractive index at 20 C 1.528. Flash point (Cleveland open cup) -195 C. Flame point (Cleveland open cup) 217-220 C.

Mixtures of any of the foregoing classes of materials are not precluded from use as the tackifier component.

The components, mineral oil, organic sulfonate, and tackifier as above described which are essential for our improved corrosion inhibiting composition, are blended in the following weight proportions:

Oil 0.5 to 4.0 parts.

Sulfonate i lpart.

Tackitier 2 to 20% based on the sulfonate.

Within the above proportioning, we prefer to use about equal amounts of the oil and the sulfonate, and about 6 to 10 percent of the tackifier based on the sulfonate present. Larger quantities of the tackifier or film forming additive than those recited may be incorporated into the oil-sulfonate blend. but such use is uneconomical since no further improvement is obtained over that re sulting from use of the specified amounts.

The resulting corrosion inhibitor composition has a viscous syrupy consistency, and while it can be applied in this condition to protect ferrous metal surfaces, as by dipping or brushing, such application is wasteful by forming unnecessarily thick films. Maximum protection efficiency is realized with a film thickness of the order of 4 mils. Put another Way, one gallon of the. composition has an efiective area coverage of approximately 50,000 sq. ft. when properly applied and thus gives a maximum protection efficiency, particularly suited for the in-and-out periods of tanker cargo loadings. Thus it is apparent that the improved protective value of our novel inhibitor compositions provides a greatly reduced 1 contamination of cargo in subsequent re-loading of the tanker; this is important for in no case is it economically feasible to clean cargo compartments for removal of the inhibitor.

To achieve a proper and efficient application of the inhibitor composition, it may either be dissolved in a volatile organic solvent such as naphtha and the like solvents generally employed in paints and other surface coatings, or, be emulsified in water. By these means a mixture suitable for spray application is produced. A solution in an organic solvent is preferred wherever such application can be made since the protection thus provided appears to be better than by means of an emulsion. A suitable spraying mixture is provided in the proportion of one gallon inhibitor dissolved in 19 gallons of naphtha, or one gallon inhibitor emulsified in a like quantity of water. These proportions'for spray mixtures are exemplary of a preferred and practical usage;- it is understood that a wide latitude in proportioning can be made without disturbing the effectiveness of the inhibitor com- ,6. position, for example the solvent or emulsion dilution for 1 part of corrosion inhibitor composition may range from about 5 to 30 parts.

Where the inhibitor composition is to be applied to the metal surfaces as an emulsion, it may be necessary in some instances to include an emulsifying or dispersing agent in the composition. In such instances, the amount of the emulsifying agent need not exceed about 2-3 percent ofthe inhibitor composition. Numerous materials are known and are commercially available for this purpose. The selection of any particular emulsifying or coupling agent is not a part of the present invention' For assistance in formulation, however, the following emulsifiers are suggested. A polyethylene ether of a long chain aliphatic alcohol of 12 to 20 carbon atoms such as is commercially available from General Dyestuffs Corporation under the trade name Emulphor is useful. Isopropyl alcohol and sodium oleate are other examples of suitable emulsion promoters.

The most common shipin the present world tanker fieet is the type T-2 oil tanker. This tanker has a capacity of 128,000 barrels of liquid cargo (16,000 tons) carried in 26 steel compartments variously sized in the shipfrom 4,000 7 to 8,000 barrels each; there are also available smaller cofferdam or bunker spaces for miscellaneous solid and liquid storage. When sailing empty, usually three of the cargo compartments are loaded with a ballast or sea water. Provision was made for treating the cargo compartments of such a ship with the inhibitor composition of our invention by means of the Butterworth spray system. The cargo handling piping system was modified to feed solutions of the inhibitor from a mixing and storage bunker through the Butterworth spray system; the inhibitor rundown is pumped back to the bunker for recirculation or storage.

A method of treating a tanker of the size noted with the corrosion inhibitors in accordance with our invention consists in mixing l0 barrels of the inhibitor composition and 190 barrels of a suitable aqueous or solvent vehicle, preferably solvent naphtha, in a storage bunker to make a 5 percent inhibitor mixture, pumping this mixture under pressure through the spray system to thoroughly wet the interior of each compartment after the cargo is unloaded. The excess inhibitorsolution draining down the compartment is removed and pumped through the cargo handling lines back' to the bunker mixing tank. If an organic solvent mixture of inhibitor is used, concentrations of the inhibitor composition therein may be as low as about I percent; moreover, the solvent solutions can beeffectively re-used after successive cargo unloadings to say, 5 or 6 times more without serious detriment by contamination with residual cargo oils or sea water. However, aqueous mixtures of the inhibitor composition are preferably made up to not less than about 5 percent concentration and generally cannot be used more than once before dumping overboard at sea.

A laboratory apparatus designed to simulate the conditions of a corrosive sea water atmosphere was employed for preliminary evaluation of inhibitor treatments which resulted in the compositions of this invention. This work was followed by shipboard treatment, under controlled conditions, of an oil tanker in regular coastal transport duty. These procedures are detailed further in the two examples which follow:

Example I The laboratory apparatus was housed in a glass jar measuring about 12 inches in diameter and 12 inches high. This jar contained a shallow layer (2 to 3 inches deep) of synthetic sea Water. The jar was fitted with a ventilated top, below which was attached a slowly rotating rack having. space for attachment of 24 mild steel test coupons; The coupons measured 1 x 8 inches and weighed approximately: grams each; these coupons were roughly abraded to expose a bright metal surface. prior to' starting a test. In the operation of this apparatus, air was bubbled at room temperature through the sea water to assure a humid sea water atmosphere about the test coupons, the corrosion. of which was further accelerated by the continuous replacement of air-oxygen therein. In each test run, several of the coupons were kept untreated for corn parative exposure purposes. The rest of the coupons were individually sprayed with an inhibitor composition in a ventilated hood at a pressure of :about lOO p. s. i. g. At periodic intervals, for instance every 7 days, a representative coupon of blank andtreated, specimens were removed for measurement of corrosionf Also at these time intervals, the treated coupons remaining in test would be sprayed again with the inhibitor composition. Except for the absence of alternating periods of; liquid hydrocarbon immersion, the schedule of this test resembles the condi tions expected on board an operating tanker; omission of the hydrocarbon. immersion cycle was intentional for purposes of shortening. the time and accelerating the course of the test.

vFigure'l graphically illustrates the results obtained in the foregoing intermittent spray laboratory testing procedure. The test was started by placing 18 coupons in the rack, none of which were initially treated with inhibitor. After 7 days slow rotation in the aeratedsea water atmosphere, the corrosion of two control coupons was measured, a group (No. l) of 4 control coupons were left untreated in the apparatus and the remaining 12 coupons were divided in 3 groupsof 4 each. Each group was given a different spray treatment, the composition for each consisting as follows: i g j Group 2.--Tlie inhibitor composition was prepared by blendingequal weight parts of 170 S. S. U. pale oil and sodium polydodecylbenzene sulfonate. The blend was emulsified in water to a concentration of 5 percentby weight.

Group 3.The inhibitor composition was prepared by blending equal weight parts of 170 S. S. U. pale oil and sodium polydodecylbenzene, and 0.2 weight part of Rosin Amine D stearate. This composition was emulsified in 7 Water. to a concentration of aboutS percent by weight.

Group 4.The inhibitor composition was prepared'as for group 3 coupons. ltwas dissolved in naphtha'to about a 5 percent concentration instead of emulsifying in water.

Having thus treated each group of coupons, they were put back into the testapparatus to be further acted upon by the corrosive conditions therein. One week later, one each of the 4 groups of coupons was removed, thoroughly cleaned and weighed to determine the corrosion loss. The remaining treated coupons were taken 1 out and. again sprayed with their respective inhibitors and replaced in the, test, apparatus. for further corrosive attack. The foregoing procedure was repeated at weekly intervals for 3 more weeks, thus providing a continuous 5-week evaluation of inhibitor elfectiveness against corrosion. results are graphicallysummarized in Figure .1, wherein the weight loss in grams'per coupon is plotted against time of exposure. The curves are numbered according to the coupon group treatment'described above. Note the improved corrosion protection provided by the inhibitor compositions of this invention even after an initial period of corrosion had set in, curves 3 and 4.. Note also the even more remarkable protectionrand arrest of corrosion attained when the improved inhibitor composition is appliediin a solvent spray, curve 4."

. Example II The partments of the tanker. These coupon racks were variously located to explore all possible degrees of cor l'OSlOIl within the compartment; the worst corrosion was found to occur at the platform level, about 10 feet below the top of the compartment. ;One of these compartments was left untreated for comparative control purposes. The other compartment was sprayed as described through the Butterworth system with the emulsified inhibitor composition employed in the previous laboratory work on group 3 test coupons, i. e., a spray emulsion consisting of 2.5 percent sodium polydodecylbenzene sulfonate, 2.5 percent 170 S. S. U. pale oil, and 0.5 percent Rosin Amine D stearatm This spray treatment was begun after a cargo unloading and similarly repeated after succcssive unloadings at approximately two-week intervals over a period of two months. At the time of each spray treatment. a pair of test coupons were removed from each compartment at the platform level for measurements of loss in weight by corrosion. Figure'2 summarizes graphically this corrosion weight loss vs; time. Note the curve showing marked decrease in corrosion for the inhibited compartment. Note also the slopes of the curves indicating the relative rate of corrosion when inhibited becomes about one-fourth that in the unprotected compartment. This same degree of protection was also found subsequently to prevail in the vapor space above the sea water ballast taken on after unloading of cargo; such vapor space is subject to the very worst of corrosive 7 inhibitor composition was calculated by subtracting the per trip. Test coupons of the size used in the laboratory were mounted on racks within two adjacent cargo comweight loss in grams per treated coupon from the weight loss of an unprotected coupon, then dividing the remainder by the weight loss of the unprotected coupon and multiplymg by according to the following formula:

Wt. loss. of unprotected coupon wt. loss of inhibited coupon tion Example III The following comparative tests were made in oncesprayed coupons run 6 days in the laboratory sea water test apparatus. A composition containing 10 percent sodium polydodecylbenzene sulfonate emulsified in water with no mineral oil present gave a corrosion protection value of only 5 percent. The beneficial effect of incorporating a volatile hydrocarbon such as naphtha in the composition is shown below. A solution of mineral oil in naphtha, but containing no sulfonate, provides protection of 21 percent. On the other hand, inhibitor compositions containing 5 percent oil and 5 percent of the above sulfonate'in naphtha solution gave a protection value of 93 percent; the corresponding. emulsion gave a protection value of 89 percent. However, when a film-forming additive or tackifier is included along with the sulfonate and the oil in the composition, the amount of the sulfonate used may be reduced to one half, occasionally even to about one fifth, and yet achieve a comparable degree of protection with a further improvement consisting in extending the service life of single inhibitor coatings five or six-fold.

Example IV The oil-soluble petroleum mahogany sulfonates (derived in about 5 percent concentration.

from sulfuric acid refining of petroleum distillate oils to produce white mineraloil) have long been used as corrosion inhibitors. Commercial formulations of mahogany sulfonate corrosion inhibitors were found to be markedly inferior to our improved inhibitor compositions based on C -polymer alkylated benzene sulfonates. Even in continuous contact with test coupons byimmersion only two days in a circulating sea water emulsion of the commercial inhibitor (less drastic than the sea water vapor phase corrosion test described in Example I), the degree of protection was very low. Thus such commercial inhibitors having an approximate composition of 15 percent sodium mahogany sulfonate, 80 percent mineral oil (viscosities ranging from 100 to 725 S. S. U. at 100 F.), 3 percent rosin soap, and 2 percent emulsifier such as diethylene glycol were used In no case did the corrosion protection exceed 45 percent even under the relatively mild corrosion conditions used.

Example V Although a decided preference has hereinbefore been shown for the sulfonates of polydodecylbenzene, we wish also to include the alkali and alkaline metal sulfonates of the lower molecular weight fractions of the alkylate .following tabulation together with the percentage protections obtained in 6-day runs with the corrosion testing apparatus of Example I. These 'compositionswere made up into 5 percent emulsion sprays and bright coupons were once treated therewith before going into test.

7 '10 S. S. U. at 100 F. or higher are used inpreparation of any of the inhibitor compositions of this invention, kerosene gas oil, and like distillates may be used as diluents to secure a desirable degree of fluidity.

While this invention is especially useful aboard ships such as oil tankers, normally used for transporting petroleum products, particularly refined products such as gasoline, kerosene, fuel oils, and the like, it may also be used aboard other ships, barges, and like vessels where conditions corrosive to metal surfaces are met and to protect off-shore drilling rigs and other equipment used in cit-shore oil production. Likewise, it is not limited to marine applications but is useful as well for rustproofing and slushing compositions such as are commonly used in the protection of stored metal parts and equipment, tank cars, storage tanks, trucks, and the like.

While particular embodiments of the invention have been described, it will be understood, of course, that the invention is not limited thereto, since many modifications may be made, and it is, therefore, contemplated to cover by the appended claims any such modifications as fall within the true spirit and scope of the invention.

We claim:

1. A corrosion inhibitor composition consisting essentially on a weight basis of about 0.5 to about 4 parts of a mineral oil, about 1 part of an oil soluble sulfonate inhibitor selected from the group consisting of alkali and alkaline earth metal sulfonates of benzene alkylated with a polymer of propylene, and about 2 to about 20 percent, based on the weight of sulfonate, of an oil soluble polar organic compound selected from the group consisting of amine and metal salts of fatty acids containing from 8 to 24 carbon atoms, characterized further in that the cation of said metal salt of the fatty acids is selected from the group consisting of magnesium and aluminum.

2. The corrosion inhibitor composition of claim 1 whereinthe alkylated benzene is polydodecylbenzene.

3. The corrosion inhibitor composition of claim 1 Test Run No 1 2 3 4 5 6 Pale Process Oil, 100 S. S. U-. Sodium dodecylbenzene sul- HB. 'Iackifler:

Rosin amine stearate Polyisobutylene Napalm Magnesium ricinoleate.-

Aluminum octoate Aluminum sternum-.- Acrylic acid ester Hydroabicty! alcohol" Emulsifying Agent:

Polyethylene ether of a long chain fatty alco- 1101 (Emulphor) 0. 026

Percentage Protection 79 83 83 81 76 61 Example VI The alkaline earth metal sulfonates of polydodecylbenzene such as Ca, Mg, and Ba were all found to be equally effective as the alkali metal sulfonates in our corrosion inhibitor components. For the production of compositions suiiiciently fluid for convenience in handling to produce solvent solutions of emulsions thereby, we find it desirable to increase the proportion of mineral oil blended therewith. For example, a viscous fluid inhibitor composition was prepared by blending weight amounts of 1 part calcium polydodecylbenzene sulfonate, 4 parts hydrocarbon oil, and 0.5 part rosin amine stearate. This inhibitor composition was dissolved in naphtha to form a 5 percent solution. Protection against corrosion in vapor phase sea water atmosphere amounted to 99.8 percent. This same degree of protection was obtained for the corresponding Ba and Mg sulfonates.

Instead of increasing the amount of mineral oil to produce a fluid inhibitor composition, kerosene may beused as a diluent. Where high viscosity oils, about 200 wherein the oil-soluble sulfonate inhibitor is an alkali metal sulfonate of benzene alkylated with a polymer of propylene.

4. The corrosion inhibitor composition of claim 1 wherein the oil-soluble sulfonate inhibitor is an alkaline earth metal sulfonate of benzene alkylated with a polymer of propylene.

5. The corrosion inhibitor composition of claim 1 wherein the alkylated benzene is dodecylbenzene.

6. The corrosion inhibitor composition of claim 1 wherein the polar organic compound is magnesium ricinoleate.

7. A corrosion inhibitor composition consisting essentially on a weight basis of about 0.5 to about 4 partsof a mineral oil, about 1 part of an oil soluble sulfonate inhibitor selected from the group consisting of alkali and alkaline earth metal sulfonates of C9-C13 alkylated benzene, and about 2 to about 20 percent based on the weight of sulfonate, of an oil soluble polar organic compound selected from the group consisting of amine and 11' a metal salts of fatty acids containing from 8 to 24 carbo atoms, characterized further in that the cation of said metal salt of the fatty acids is selected from the group consisting of magnesium and aluminum.

8. A corrosion inhibitor composition consisting essentially on a weight basis of about 0.5 to about 4 parts of a mineral oil, about 1 part of an oil soluble sulfonate inhibitor selected from the group consisting of alkali and alkaline earth metal sulfonates of benzene alkylated with a polymer of propylene, and about 2 to about 20 percent,

based on the Weight of sulfonate, of an oil soluble polar organic compound selected from the group consisting of amine and metal salts of fatty acids containing from'8 to 24 carbon atoms, characterized further in that the cation of said metal salt of the fatty acids is selected from the group consistingof magnesium and aluminum.

9. A corrosion inhibitor compositon consisting essentially on a weight basis of about 0.5 to about 4 parts of a mineraloil, about 1 part of an alkali metal sulfonate of polydodecylbenzene, and about 2 to about 20 percent, based on the weight of sulfonate, of an oil soluble polar organic compound selected from the group consisting of amine and metal salts of fatty acids containing from 8 to 24 carbon atoms, characterized further in that the cation of said metal salt of the fatty acids is selected from the group consisting of magnesium and aluminum.

(The corrosion inhibitor composition of claim 9 wherein the alkali metal sulfonate of polydodecylbenzene is sodium polydodecylbenzene sulfonate.

11. A corrosion inhibitor composition consisting essentially on a weight basis of about 0.5 to about 4 parts of a mineral oil, about 1 part of alkaline earth metal sulfonate of polydodecylbenzene, and about '2 to about 20 percent, based on the weight of sulfonate, of an oil soluble polar organic compound selected from the group consisting of amine and metal salts of fatty acids containing from 8 to 24 carbon atoms, characterized further 12 wherein the alkaline earth metal sulfonate of polydodecylbenzene is barium polydodecylbenzene sulfonate.

15. A corrosion inhibitor composition consisting essentially on a weight basis of about 0.5 to about 4 parts of a mineral oil, about 1 part of an alkali metal sulfonate of dodecylbenzene, and about 2 to about 20 percent, based on the weight of sulfonate, of an oil soluble polar organic compound selected from the group consisting of amine and metal salts of fatty acids containing from 8 to 24 carbon atoms, characterized further in that the cation of said metal salt of the fatty acids is selected from the group consisting of magnesium and aluminum.

16. The corrosion inhibitor composition of claim wherein the alkali metal sulfonate of dodecylbenzene is sodium dodecylbenzene sulfonate.

17. A corrosion inhibitor composition consisting essentially on a weight basis of about 0.5 to about 4 parts of in that the cation of said metal salt of the fatty acids is selected from the group consisting of magnesium and aluminum.

12. The corrosion inhibitor composition of claim 11 wherein the alkaline earth metal sulfonate of polydodecylbenzene is magnesium polydodecylbenzene sulfonate'll 14. The corrosion inhibitor composition of claim 11 a mineral oil, about 1 part of an alkaline earth metal sulfonate of dodecylbenzene, and about 2 to about 20 percent, based on the weight of sulfonate, of an oil soluble polar organic compound selected from the group consisting of amine and metal salts of fatty acids containing from 8 to 24 carbon atoms, characterized further in that the cation of said metal salt of the fatty acids is selected from the group consisting of magnesium and aluminum.

18. A corrosion inhibitor composition consisting essentially, on a weight basis, of about .5 to about 4 parts of a mineral oil, about 1 part of an oil soluble sulfonate inhibitor selected from the group consisting of alkali and alkaline earth metal sulfonates of benzene, alkylated with a polymer of propylene, and about 2 to 20 percent, based on the weight of said sulfonate, of rosin amine stearate.

References Cited in the file of this patent UNITEDSTATES PATENTS 2,398,212 Durgin Apr. 9, 1946 2,402,793 White et al. June 25, 1946 2,430,846 Morgan Nov. 11, 1947 2,453,833 Davis et al. Nov. 16, 1948 2,484,010 Bried Oct. 11, 1949 2,517,720 Schaad Aug.-8, 1950 2,540,534 Kolfenbach et al. Feb. 6, 1951 2,566,068 Morgan et al. Aug. 28, 1951 2,598,949 Walker et al. June 3, 1952 2,629,676 Prutton Feb. 24, 1953 

1. A CORROSION INHIBITOR COMPOSITION CONSISTING ESSENTIALLY ON A WEIGHT BASIS OF ABOUT 0.5 TO ABOUT 4 PARTS OF A MINERAL OIL, ABOUT 1 PART OF AN OIL SOLUBLE SULFONATE INHIBITOR SELECTED FROM THE GROUP CONSISTING OF ALKALI AND ALKALINE EARTH METAL SULFONATES OF BENZENE ALKYLATED WITH A POLYMER OF PROPYLENE, AND ABOUT 2 TO ABOUT 20 PERCENT, BASED ON THE WEIGHT OF SULFONATE, OF AN OIL SOLUBLE POLAR ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF AMINE AND METAL SALTS OF FATTY ACIDS CONTAINING FROM 8 TO 24 CARBON ATOMS, CHARACTERIZED FURTHER IN THAT THE CATION OF SAID METAL SALT OF THE FATTY ACIDS IS SELECTED FROM THE GROUP CONSISTING OF MAGNESIUM AND ALUMINUM. 